APPLICANT'S ABSTRACT: The purpose of this study is to identify and distinguish the relationship between gang violence and illicit drug use among Mexican American youth and young adults (ages 14 to 25) in San Antonio and Laredo. These predominantly Mexican American cities have experienced an unprecedented increase in violence and illicit drug use among youth. This study will examine the epidemiology of violence and drug use among youth in two public housing projects in San Antonio and three neighborhood barrios in Laredo. Although all are low-income areas, the San Antonio and Laredo sites differ along several social and economical variables. This difference will serve as the context within which the following aims will be comparatively addressed: (a) identify and determine the size of gangs and other high risk groups of youth (palomillas, klikas, etc.); (b) determine the characteristics of gangs and other high risk groups, including membership criteria, organizational structure, goals, norms and values, and primary activities; (c) specify the extent and determinants of illicit drug use and violence among individual gang members and other high risk youth; (d) study the relationship of illicit drugs and violent behavior as a function of gang or peer group membership; (e) specify the relationship of gang members and other youth to community institutions and groups such as family networks, social service agencies, churches, businesses and older established neighborhood based criminal networks; (f) distinguish how social economic indicators effect family structure, peer group formulation, community institutions, drug use and drug- related violence. The study will utilize three data collection methods: (a) twenty-four focus group sessions will be conducted in San Antonio and Laredo; (b) community survey consisting of life histories/intensive interviews will be conducted with a sample of 250 youth involved in drugs and violence (gang and non-gang members) from the two cities (San Antonio = 125 and Laredo = 125); (c) social indicators from census sources, state and local agencies including criminal justice data. These data methods collect both qualitative and quantitative data. The general approach to the data analysis will be through a "multi- level linear model."